In: Statistics and Probability
Caption: Princess Foods wants to determine if there is a relationship in the amount a household spends on prepared foods to family size and income. Parthika: Well, we still have data collected from a previous marketing study. Let’s use that. We have an Excel file. I am sure we can find the spreadsheet. It should have the exact information we need. Liwei: Yes, this could be interesting. We may find enough evidence to rethink the meal preparation kits again. Bonnie: Great idea. We need to know it the data is a good fit and what the exact relationship is between the dependent variable and the independent variables. We can use this information to help us design perhaps a new line of prepared frozen foods. ParthikaYes, what about the prepackaged salad bowls. We really need to see this data. Bonnie: Yes, let’s get right on this.
Please use the below data to determine the equation that represents the relationship and explain the goodness of fit. Based on the data, write a detailed memo/explanation and interpret the results. How might this data be used?
| Dollars spent on Prepared food | Family size | Gross monthly income |
| 495.86 | 4 | 3126 |
| 642.77 | 5 | 3933 |
| 364.81 | 3 | 1925 |
| 619.3 | 5 | 3736 |
| 238.71 | 1 | 1453 |
| 378.94 | 2 | 2538 |
| 302.58 | 1 | 1798 |
| 231.74 | 2 | 1189 |
| 428.67 | 3 | 2247 |
| 286.99 | 3 | 1460 |
| 268.81 | 1 | 1567 |
| 329.81 | 2 | 1622 |
| 627.25 | 5 | 3828 |
| 421.52 | 3 | 2782 |
| 656.38 | 5 | 3978 |
| 400.64 | 3 | 2493 |
| 603.41 | 6 | 3753 |
| 560.69 | 4 | 3778 |
| 623 | 5 | 3609 |
| 416.12 | 2 | 2262 |
| 323.9 | 1 | 1966 |
| 418.78 | 3 | 2736 |
| 506.46 | 4 | 3274 |
| 552.53 | 2 | 3480 |
| 586.46 | 4 | 3741 |
| 637.18 | 8 | 3684 |
| 244.49 | 2 | 1476 |
| 507.19 | 5 | 2835 |
| 512.56 | 5 | 2873 |
| 312.89 | 1 | 1618 |
| 329.05 | 2 | 1565 |
| 243.49 | 2 | 1582 |
| 560.37 | 8 | 3380 |
| 599.9 | 5 | 3922 |
| 657.09 | 5 | 3845 |
| 394.82 | 2 | 2233 |
| 556.42 | 4 | 3098 |
| 596.05 | 8 | 3707 |
| 365.8 | 4 | 2071 |
| 489.08 | 3 | 3166 |
Excel > Data > Data Analysis > Regression > Give X and Y values range (select lables if present) > OK
| SUMMARY OUTPUT | ||||||||
| Regression Statistics | ||||||||
| Multiple R | 0.980501258 | |||||||
| R Square | 0.961382717 | |||||||
| Adjusted R Square | 0.959295296 | |||||||
| Standard Error | 27.83077172 | |||||||
| Observations | 40 | |||||||
| ANOVA | ||||||||
| df | SS | MS | F | Significance F | ||||
| Regression | 2 | 713455.378 | 356727.689 | 460.5601123 | 7.16905E-27 | |||
| Residual | 37 | 28658.41861 | 774.5518544 | |||||
| Total | 39 | 742113.7966 | ||||||
| Coefficients | Standard Error | t Stat | P-value | Lower 95% | Upper 95% | Lower 95.0% | Upper 95.0% | |
| Intercept | 61.42165489 | 14.32509969 | 4.287694761 | 0.00012396 | 32.39624586 | 90.44706391 | 32.39624586 | 90.44706391 |
| Family size | 9.693091949 | 3.607684799 | 2.686790141 | 0.01074241 | 2.3832282 | 17.0029557 | 2.3832282 | 17.0029557 |
| Gross monthly income | 0.132165589 | 0.007535354 | 17.5393996 | 1.6178E-19 | 0.116897511 | 0.147433667 | 0.116897511 | 0.147433667 |
Dollars spent on Prepared food = 61.4217 + 9.6931 * Family size + 0.1322 * Gross monthly income
If family size increases 1 unit then Dollars spent on Prepared food increases 9.6931 units when other independent variables constant
If Gross monthly income increases 1 unit then Dollars spent on Prepared food increases 0.1322 units when other independent variables constant
If Independent variables are equal to 0 then Y intercept is the mean value of Dollars spent on Prepared food
R = 0.9805, means Strong and positive correlation present
R^2 = 0.9614, means 96.14% of variation in Y variable is explained by regression model
R^2 represents goodness of fit also. If it is nearer to 1, which means it is best fit